The present invention relates to a friction applying apparatus which moves sliding members along contacted members such as guide rails, and generates friction by forcing the sliding members to the contacted members, and relates to a linear guide apparatus provided with the friction applying apparatus.
In a moving table incorporated in a machine tool or an industrial machine moving at relatively high speed by ball screws or linear motors, a linear guide apparatus has been used for guiding their movement.
This kind of linear guide apparatus comprises a guide rail extending in one direction and a slider in movable combination with the guiding rail, and the slider is mounted thereon with the moving table, so that the moving table moves along the guiding rail together with the slider.
The guiding rail is formed at its outside with rolling grooves for rolling elements. The slider at its inside surfaces with rolling grooves for the rolling elements that repectively opposite to the rolling grooves of the guide rail. The plurality of rolling elements such as balls are rotatably charged between the rolling grooves of the rail and the slider, so that the balls circulate therebetween in response to the movement of the slider relative to the guide rail.
The linear guide apparatus as mentioned above is equipped with the friction applying apparatus for heightening attenuation (rigidity) of the moving table. The friction applying apparatus comprises the sliding members furnished in opposition to the outer surfaces of the guiding rail as the contacted members and pressing units for urging the sliding members against the guiding rail, and the sliding members moves along the guiding rail together with the moving table.
When heightening attenuation of the moving table, the sliding member is pressed to the guiding rail by the pressing unit, and owing to friction force by pressing, vibration of the moving table is attenuated to increase rigidity.
As the sliding members of the friction applying apparatus, metals of sintered alloys of cast iron or copper group are generally employed, and in view of abrasion resistance, materials having hard quality are selected.
However, the hard material is ordinarily high in elastic modulus, and therefore, when pressing the sliding member to the guiding rail, it is difficult to uniformly contact an allover contacting face of the sliding member to the guiding rail, and actually its one-sided part of the contacting face has a partially high pressure and is earlier worn to shorten a serving life of the friction applying apparatus. Further, there is possibility that worn powders of the guiding rail or sliding member invade into the linear guide apparatus and cause obstacles in function of the linear guide apparatus.